bug#22336: 25.0.50; cl-generic.el features are not documented in ELisp manual

[Eli Zaretskii]

> Date: Sat, 09 Jan 2016 11:06:52 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> 
> The generics should be prominently documented either in the ELisp
> manual.  Emacs 25.1 should have them documented, due to their wide usage
> in the core packages and elsewhere.

I made this bug block v25.1 release.

If someone can describe the relevant stuff, but is afraid the text
won't be up to the standards of the manual, or isn't proficient enough
with Texinfo, please send the text, and I volunteer to edit it into
the appropriate form for inclusion in the manual.

IOW, don't bother yourself with technicalities; just produce the
contents.

TIA